This conversion was done by Family and Performance Boating on 01/05.This conversion does not require the replacement of the Y-pipe.We sell this complete tuned port system* in kit form, for just $1164.99*.*(includes: New manifolds, new risers, new mercruiser elbows (14478T01), gaskets, bolts, exhaust hoses, and clamps)Click the link www.boatstoreonline.com/glmexhaust.html(*Mercruiser list price $1699.63)Also available in aluminum!